While effective treatments for malaria exist, parasite resistance to these drugs is growing rapidly, and there is a critical need for new mechanisms to combat this disease. Several recent studies indicate that the motile and invasive machinery of the parasite represents a promising new target for drug discovery. In order to facilitate future drug discovery projects targeting the malarial motor and invasion machinery, this proposal aims to use an interdisciplinary approach to elucidate the structural features of a part of this complex expressed in Plasmodium falciparum merozoites - the invasive blood stage of this parasite, andthe causative agent of cerebral malaria and the majority of malarial mortality. Plasmodia, like other apicomplexan protozoa, employ a mechanism of substrate-dependent gliding motility that does not depend on cilia or flagella. Gliding and host cell invasion are crucial parasite functions and increasingly appear to be driven by an actin/myosin motor located beneath the organism's plasma membrane. Myosin generates movement by forcefully displacing actin. In Plasmodium merozoites, this force is transmitted - viatheactin-binding, glycolytic enzyme, aldolase - to MTRAP, a type I trans-membrane molecule bearing adhesive domains capable of interacting with host-cell surfaces. The parasite uses this force to actively invade human red blood cells. This proposal aims to elucidate the structural features of the MTRAP-aldolase interaction in Plasmodium falciparum merozoites via the biochemical characterization of this complex in vitro and the three-dimensional resolution of the MTRAP-aldolase interface in silico. A combination of site-directed mutagenesis, homology modeling, and computational docking will be used to identify and visualize key contacts between the two proteins. The detailed picture of the structural basis for the MTRAP-aldolase interaction thus obtained will serve as the platform for the future rational design of anti-malarial agents. PUBLIC HEALTH RELEVANCE: Malarial disease affects hundreds of millions of people worldwide - afflicting them with anemia, excruciating pain, fever, and in severe cases, cerebral blood vessel occlusion, organ damage, and death. The research proposed here serves as an ideal training opportunity in computational biology and the biochemistry of a global infectious disease, while simultaneously increasing the current knowledge of a key aspect of malarial biology, and facilitating the design of novel, safe, and effective anti-malarial agents.